xor swap trick was useful in older simd (sse1/sse2) when based on some condition you want to sw...

mmozeiko • today at 6:11 AM • 1 reply • view on HN

xor swap trick was useful in older simd (sse1/sse2) when based on some condition you want to swap values or not:

  tmp = (a ^ b) & mask
  a ^= tmp
  b ^= tmp

If mask = 0xfff...fff then a/b will be swapped, otherwise if mask = 0 then they'll remain the same.

CJefferson • today at 6:39 AM

Oh, that is cool, I’ve never seen that. I might add that to an extended version of the post sometime, I’ll be sure to credit you.

alt Hacker News